Cordycord's epic tube frame battery
10-17-2012, 12:35 PM
#1
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Cordycord's epic tube frame battery
mod note: split off from " Cordycord's epic tube frame build" thread
Oh, and that battery? Epic.
When I first picked it up, my initial thought was "This is a pretty neat mock-up. When will you have a real one available to test?"
That thing really does weigh less than Pusha's ego.
Oh, and that battery? Epic.
When I first picked it up, my initial thought was "This is a pretty neat mock-up. When will you have a real one available to test?"
That thing really does weigh less than Pusha's ego.
Last edited by Joe Perez; 10-20-2012 at 10:42 AM. Reason: Split
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10-17-2012, 12:57 PM
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Yeah, but it mostly consists of hot air. The ratio of mass to volume or mass to surface-area is hugely askew.
What really impresses me about the battery isn't actually the size or weight per-se. I think the one I held was 12v(ish) at 16Ah. The battery on my bike is 52v at 11.5Ah, and it probably weighs about 3-4x what the Braille battery does, so that kind of makes sense.
The amazing thing about that battery is the electro-chemical properties.
First, it's gotta be capable of delivering a couple of hundred amps for at least several seconds, and that is *WAY* outside the normal profile for a lithium battery. The LiPo packs that the RC airplane crowd use are similar, I guess, but you don't normally find batteries with 20c permissible discharge ratings in automotive applications.
And the *really* cool thing is that it doesn't appear to require any special provisions for charging. You hook it up, and it charges through the same terminals that it discharges through, just like a "normal" car battery. You can't just hook an unregulated voltage source to a lithium battery and expect it to charge itself normally without blowing up, which is why most lithium batteries have more than two terminals and interface with fancy chargers. (The battery on my bike, even though it has an on-board BMS, still requires separate connections for charge vs. discharge.)
I can't resolve those two features in my head. What kind of circuit can you built that allows for common-port charge / discharge and is also capable of passing 200 amps or more on the discharge phase?
Anyway, I'm threadjacking. Sorry about that.
What really impresses me about the battery isn't actually the size or weight per-se. I think the one I held was 12v(ish) at 16Ah. The battery on my bike is 52v at 11.5Ah, and it probably weighs about 3-4x what the Braille battery does, so that kind of makes sense.
The amazing thing about that battery is the electro-chemical properties.
First, it's gotta be capable of delivering a couple of hundred amps for at least several seconds, and that is *WAY* outside the normal profile for a lithium battery. The LiPo packs that the RC airplane crowd use are similar, I guess, but you don't normally find batteries with 20c permissible discharge ratings in automotive applications.
And the *really* cool thing is that it doesn't appear to require any special provisions for charging. You hook it up, and it charges through the same terminals that it discharges through, just like a "normal" car battery. You can't just hook an unregulated voltage source to a lithium battery and expect it to charge itself normally without blowing up, which is why most lithium batteries have more than two terminals and interface with fancy chargers. (The battery on my bike, even though it has an on-board BMS, still requires separate connections for charge vs. discharge.)
I can't resolve those two features in my head. What kind of circuit can you built that allows for common-port charge / discharge and is also capable of passing 200 amps or more on the discharge phase?
Anyway, I'm threadjacking. Sorry about that.
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10-18-2012, 03:36 AM
#6
Yeah, but it mostly consists of hot air. The ratio of mass to volume or mass to surface-area is hugely askew.
What really impresses me about the battery isn't actually the size or weight per-se. I think the one I held was 12v(ish) at 16Ah. The battery on my bike is 52v at 11.5Ah, and it probably weighs about 3-4x what the Braille battery does, so that kind of makes sense.
The amazing thing about that battery is the electro-chemical properties.
First, it's gotta be capable of delivering a couple of hundred amps for at least several seconds, and that is *WAY* outside the normal profile for a lithium battery. The LiPo packs that the RC airplane crowd use are similar, I guess, but you don't normally find batteries with 20c permissible discharge ratings in automotive applications.
And the *really* cool thing is that it doesn't appear to require any special provisions for charging. You hook it up, and it charges through the same terminals that it discharges through, just like a "normal" car battery. You can't just hook an unregulated voltage source to a lithium battery and expect it to charge itself normally without blowing up, which is why most lithium batteries have more than two terminals and interface with fancy chargers. (The battery on my bike, even though it has an on-board BMS, still requires separate connections for charge vs. discharge.)
I can't resolve those two features in my head. What kind of circuit can you built that allows for common-port charge / discharge and is also capable of passing 200 amps or more on the discharge phase?
Anyway, I'm threadjacking. Sorry about that.
What really impresses me about the battery isn't actually the size or weight per-se. I think the one I held was 12v(ish) at 16Ah. The battery on my bike is 52v at 11.5Ah, and it probably weighs about 3-4x what the Braille battery does, so that kind of makes sense.
The amazing thing about that battery is the electro-chemical properties.
First, it's gotta be capable of delivering a couple of hundred amps for at least several seconds, and that is *WAY* outside the normal profile for a lithium battery. The LiPo packs that the RC airplane crowd use are similar, I guess, but you don't normally find batteries with 20c permissible discharge ratings in automotive applications.
And the *really* cool thing is that it doesn't appear to require any special provisions for charging. You hook it up, and it charges through the same terminals that it discharges through, just like a "normal" car battery. You can't just hook an unregulated voltage source to a lithium battery and expect it to charge itself normally without blowing up, which is why most lithium batteries have more than two terminals and interface with fancy chargers. (The battery on my bike, even though it has an on-board BMS, still requires separate connections for charge vs. discharge.)
I can't resolve those two features in my head. What kind of circuit can you built that allows for common-port charge / discharge and is also capable of passing 200 amps or more on the discharge phase?
Anyway, I'm threadjacking. Sorry about that.
I can't believe how many people geek out about the battery. Everyone who comes in the shop and sees it makes a comment. One neat thing is that since it charges faster than a standard battery, it takes less alternator draw.
In a few years I think all the batteries will be like the Braille, mainly because it's "green"'; No caustic chemicals. If Uncle Sam can mandate curlie cue bulbs, lead acid batteries will be going the way of the dinosaur before long.
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10-19-2012, 11:42 AM
#8
Plug 'em in and go. 
Martin from Monster Miata stopped by the shop last night at around 10:30, and he and his buddy Bill were also geeking out about the battery. Jeez, I have a perfectly good tube frame car sitting 10 feet away, and they just want to pick up a carbon-cased battery.
BTW, averaging three hours of sleep a night for the past three nights. I've got Roman Maguinez down here from LA with "the Davids", which are his two crew members who help him out. I think you can guess their names. David is also my main fabricator for the Catfish, so we have three David's hovering over the car at any given moment.
We went home last night after the car fired up for the first time in the new frame. We hope to make it a roller today.
Martin from Monster Miata stopped by the shop last night at around 10:30, and he and his buddy Bill were also geeking out about the battery. Jeez, I have a perfectly good tube frame car sitting 10 feet away, and they just want to pick up a carbon-cased battery.BTW, averaging three hours of sleep a night for the past three nights. I've got Roman Maguinez down here from LA with "the Davids", which are his two crew members who help him out. I think you can guess their names. David is also my main fabricator for the Catfish, so we have three David's hovering over the car at any given moment.
We went home last night after the car fired up for the first time in the new frame. We hope to make it a roller today.
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10-19-2012, 01:21 PM
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Fair enough. New thread created, battery related ****-stroking moved.
Hahaha.
I honestly felt a little self-conscious geeking out over the battery (and the secret thing) while I was there, but I justified it to myself by saying that the black frame was busy being worked on, and nobody had had the common decency to install a seat into the unpainted frame before I got there so that I'd have a chance to sit in it.
So thanks for that. (I'm back to judging you harshly mode.
)
Killer!
That's seriously excellent progress in just a couple of days.
I wish I knew.
The weird thing is that it only has two terminals. That's totally normal for a lead-acid battery- you shove current back into it through the same terminals that you use to take current out of it, and the battery's ESR automatically takes care of "regulating" the charge. From a practical standpoint, it's pretty much impossible to over-charge a lead-acid battery, and it doesn't require much in the way of regulation. Just limit the charge voltage to about 14-14.5v, and the current will self-limit.
Lithium batteries (of which there are actually several different chemistries) are a bit more complex. You have to very carefully control two specific factors:
Break either of these rules and they go from cute little fuzzballs to scary green monsters that rip up the town and drive Mr. Futterman's snowplow right through the front of his house.
Single-cell lithium batteries (of the sort found in cell-phones) typically have a minimum of three terminals, where one is a temperature sensor, and they rely upon the assumption that the phone they're plugged into contains a charge controller and discharge limiter.
Multi-cell batteries are more complicated, since the voltage rules apply on a PER-CELL basis. You can't just sense the voltage of the whole pack, you've gotta make sure that no individual cell within a series string goes above or below the threshohold values.
Cheap LiPo packs, such as those used in RC airplanes, typically rely on fancy external chargers with multi-pin connectors, and they still catch on fire sufficiently often that the manufacturers also sell heavy, explosion-proof charging bags and recommend that you never leave them unattended.
Better LiMn and LiFe packs (such as the one on my bike) have on-board charge/discharge controllers. They take care of the per-cell regulation during the charge cycle, and they shut themselves off if the voltage drops too low during the discharge phase.
This battery confuses me, as it doesn't seem to have affordances for either of those things.
I suppose, in theory, that it could contain a discharge cutoff controller, but that would presuppose that it also contains a bank of MOSFETs sufficiently large and low-resistance that they can pass a couple of hundred amps without exploding.
On the charge side, that's where it really gets weird. Typically, we expect that the charging will be done through a separate port, so that the charge can be regulated and shut down once the battery is "full". But this battery doesn't have separate charge and discharge ports.
So I just dunno. I'm sure it works great, but I'll be damned if I can figure out what's actually inside it.
I honestly felt a little self-conscious geeking out over the battery (and the secret thing) while I was there, but I justified it to myself by saying that the black frame was busy being worked on, and nobody had had the common decency to install a seat into the unpainted frame before I got there so that I'd have a chance to sit in it.
So thanks for that. (I'm back to judging you harshly mode.
)
We went home last night after the car fired up for the first time in the new frame. We hope to make it a roller today.
That's seriously excellent progress in just a couple of days.
I wish I knew.
The weird thing is that it only has two terminals. That's totally normal for a lead-acid battery- you shove current back into it through the same terminals that you use to take current out of it, and the battery's ESR automatically takes care of "regulating" the charge. From a practical standpoint, it's pretty much impossible to over-charge a lead-acid battery, and it doesn't require much in the way of regulation. Just limit the charge voltage to about 14-14.5v, and the current will self-limit.
Lithium batteries (of which there are actually several different chemistries) are a bit more complex. You have to very carefully control two specific factors:
- The charging current and voltage must both be carefully regulated, and
- They must never be discharged to below a certain voltage.
Break either of these rules and they go from cute little fuzzballs to scary green monsters that rip up the town and drive Mr. Futterman's snowplow right through the front of his house.
Single-cell lithium batteries (of the sort found in cell-phones) typically have a minimum of three terminals, where one is a temperature sensor, and they rely upon the assumption that the phone they're plugged into contains a charge controller and discharge limiter.
Multi-cell batteries are more complicated, since the voltage rules apply on a PER-CELL basis. You can't just sense the voltage of the whole pack, you've gotta make sure that no individual cell within a series string goes above or below the threshohold values.
Cheap LiPo packs, such as those used in RC airplanes, typically rely on fancy external chargers with multi-pin connectors, and they still catch on fire sufficiently often that the manufacturers also sell heavy, explosion-proof charging bags and recommend that you never leave them unattended.
Better LiMn and LiFe packs (such as the one on my bike) have on-board charge/discharge controllers. They take care of the per-cell regulation during the charge cycle, and they shut themselves off if the voltage drops too low during the discharge phase.
This battery confuses me, as it doesn't seem to have affordances for either of those things.
I suppose, in theory, that it could contain a discharge cutoff controller, but that would presuppose that it also contains a bank of MOSFETs sufficiently large and low-resistance that they can pass a couple of hundred amps without exploding.
On the charge side, that's where it really gets weird. Typically, we expect that the charging will be done through a separate port, so that the charge can be regulated and shut down once the battery is "full". But this battery doesn't have separate charge and discharge ports.
So I just dunno. I'm sure it works great, but I'll be damned if I can figure out what's actually inside it.
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10-20-2012, 03:30 AM
#13
There is one more battery coming out called the U1R. It's a direct Miata replacement battery that will weigh 5lbs and cost about $369. Perfect daily driver/weekend warrior battery, with all the benefits of light weight, long life, more cranking power, faster recharge (less alternator draw), etceteras.
OK, infomercial over. I've got my kick-*** battery, but it sounds like there will be some new ones coming out very soon that are within reach budget-wise and give the same benefits.
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11-04-2012, 12:47 AM
#14
Here's the new Braille battery
This is what Braille had at the show. It's the same size at the stock Miata battery, yet is lithium and weighs just 6.6lbs. Braille won a SEMA award for it, as on top of all the benefits (10 year life, 900cca, "green" lithium, etceteras) the cost is around $350.
I was at the booth listening to their pitch during the whole show:
--lithium retains a strong charge up until drop-off when it's nearly drained. Lead/acid batteries drain slowly so that your car stops working once the battery hits 10-ish volts.
--charges faster so there's less alternator drain on horsepower
--faster startup
--LIGHT. 6.6lbs. No need to skip that Double Double with fries if you get this battery
--same form factor as OEM--my spendy battery is much smaller, and requires a different battery mount. This one bolts right in with no modifications.
--DOT and Rohs approved, which is apparently impossible for AGM batteries.
This would appear to be the shiznit.
I was at the booth listening to their pitch during the whole show:
--lithium retains a strong charge up until drop-off when it's nearly drained. Lead/acid batteries drain slowly so that your car stops working once the battery hits 10-ish volts.
--charges faster so there's less alternator drain on horsepower
--faster startup
--LIGHT. 6.6lbs. No need to skip that Double Double with fries if you get this battery
--same form factor as OEM--my spendy battery is much smaller, and requires a different battery mount. This one bolts right in with no modifications.
--DOT and Rohs approved, which is apparently impossible for AGM batteries.
This would appear to be the shiznit.
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